Many medical complications are created by the total or even partial blockage of blood vessels of the body. The primary cause of these complications is, of course, the reduction or cessation of blood flow through the blocked vessels to the particular biological tissue which is serviced by the vessel. Most commonly, a blockage, or stenosis, is formed in an artery as a result of plaque build-up in the artery. Further, it is not uncommon for several stenoses to occur sequentially in a single artery or to develop near one another in branches of a common central artery.
Traditionally, removal of stenotic material from the arterial vessels of a patient has required direct surgical access to the involved vessel. For example, in a typical coronary by-pass procedure, the surgeon will actually replace the stenotic segment of the involved artery with a graft artery taken from another part of the patient's body. Generally, although techniques of this type may be highly effective, and even life-saving, they are costly in terms of patient trauma.
As an alternative to methods requiring direct access to the involved vessel, several methods, or procedures, have been developed wherein access to the stenosis is achieved indirectly through a peripheral artery. Many of these methods involve insertion of a dilation device into the peripheral artery. After insertion, the device is advanced through the peripheral artery until it reaches the site of the stenosis. The device is then manipulated to dilate the stenosis thereby improving the flow of blood through the stenotic segment.
An example of a dilation-type procedure, which is known as balloon angioplasty, is disclosed in U.S. Pat. No. Re. 33,561 which issued to Levy for an invention entitled "BALLOON AND MANUFACTURE THEREOF." As taught by Levy, a deflated dilatation balloon is inserted into the vessel and is placed across the stenosis. Once the balloon is properly positioned, it is then inflated to dilate the artery and thereby clear the stenosis.
Recent studies have indicated that for procedures wherein a stenosis is to be dilated, such as for an angioplasty procedure, the efficacy of the dilatation is enhanced by first incising the material which is creating the stenosis. With this knowledge, several devices for clearing blocked arteries have been proposed. For example, U.S. Pat. No. 4,273,128 which issued to Lary for an invention entitled "CORONARY CUTTING AND DILATING INSTRUMENT" discloses a surgical instrument which both incises and dilates a stenosis. As another example, U.S. Pat. No. 5,209,799 which issued to Vigil for an invention entitled "METHOD FOR MANUFACTURING A FOLDING BALLOON CATHETER" discloses a folding angioplasty balloon with attached atherotomes.
While angioplasty and by-pass surgery procedures, as disclosed above, are efficacious for their intended purposes, it happens that less aggressive methods may also be appropriate and just as effective for removing or clearing a stenosis from the vessel of a patient. Moreover, less aggressive methods may be preferable. This is particularly so where shorter, and perhaps more numerous, stenoses are involved. It is also the case that both angioplasty and by-pass surgery procedures necessarily result in some cessation of blood flow within the involved vessel during the course of the procedure. It happens that less aggressive methods may effectively remove stenotic segments while still maintaining blood flow within the involved vessel.
In light of the above it is an object of the present invention to provide a device and method for incising and dilating a stenosis in a vessel of a patient which is particularly efficacious for shorter stenotic blockages in the vessel. Another object of the present invention is to provide a device and method for incising and dilating a stenosis in a vessel of a patient which can be used with either direct or indirect access to the stenosis. Still another object of the present invention is to provide a device and method for incising and dilating a stenosis in a vessel of a patient which can be effectively used to augment a more aggressive procedure such as either angioplasty, athrectomy or by-pass surgery. Yet another object is to provide a device which can cut and dilate numerous areas of stenoses in a single vessel and which is replaceable with a smaller identical apparatus which will pass through proximal stenoses that have been previously removed to clear stenoses in the smaller distal position of the same vessel. Yet another object of the present invention is to provide a device for incising and dilating a stenosis in a vessel of a patient which maintains adequate blood flow within the involved vessel during the process of incision and dilation. Yet another object of the present invention is to provide a device for incising and dilating a stenosis in a vessel of a patient which is relatively simple to manufacture, easy to use, and comparatively cost effective.